Images

After the May 18, 1980 eruption, Mount St. Helens' elevation was only 8,364 feet (2,550 meters) and the volcano had a one-mile-wide (1.5 kilometers) and approximately 600 m (2000 ft) deep horseshoe-shaped crater. View here is from the northwest.

Mount St. Helens soon after the May 18, 1980 eruption, as viewed from Johnston's Ridge.

Mount St. Helens soon after the May 18, 1980 eruption, as viewed from Johnston's Ridge.

Blowdown of trees from the shock-wave of the directed (lateral) blast from the May 18, 1980 eruption of Mount St. Helens. Elk Rock is the peak with a singed area on the left.

During the May 18, 1980 eruption, at least 17 separate pyroclastic flows descended the flanks of Mount St. Helens. Pyroclastic flows typically move at speeds of over 60 miles per hour (100 kilometers/hour) and reach temperatures of over 800 Degrees Fahrenheit (400 degrees Celsius).

Pyroclastic flow during August 7, 1980, Mount St. Helens eruption. The view is from Johnston Ridge, located 8 km (5 mi) north of Mount St. Helens.

July 22, 1980 eruption of Mount St. Helens sent pumice and ash 6 to 11 mi (10-18 km) into the air, and was visible in Seattle, Washington (100 mi/160 km north).

The Washington State Highway 99 (Old Pacific Highway) Bridge survived the May 18, 1980 lahar. Here, the front of the mudflow from the South Fork Toutle River passed by at about 1:00 p.m. P.D.T. on May 18; the mudflow from the North Fork of the Toutle River arrived at about 8:30 p.m. High-mudflow marks may still be visible on nearby trees.

Mudline left on tree by May 18, 1980 lahars from Mount St. Helens near the Old Highway 99 bridge across Toutle River, geologist 6 ft tall.

Ash from the May 18, 1980 eruption of Mount St. Helens covering the ground and road at a farm in Connell, Washington, approximately 300 km (180 mi) from the volcano.

For more than nine hours a vigorous plume of ash erupted, eventually reaching 20-25 km (12-15 mi) above sea level. By early May 19, the devastating eruption was over.

On May 18, 1980, at 8:32 a.m. Pacific Daylight Time, a magnitude 5.1 earthquake shook Mount St. Helens. The bulge and surrounding area slid away in a gigantic rockslide and debris avalanche, releasing pressure, and triggering a major pumice and ash eruption of the volcano. Thirteen-hundred feet (400 meters) of the peak collapsed or blew outwards.

The May 18, 1980 eruption of Mount St. Helens, Washington, generated lahars that swept down river valleys. The St. Helens bridge on Highway 504 was carried over a quarter-mile (a half-kilometer) downstream and partially buried.  The USGS Cascades Volcano Observatory continues to monitor Mount St. Helens and other very high threat volcanoes. Photo by R.L.

May 18, 1980 eruption of Mount St. Helens from southwest. Note the pyroclastic density currents spilling over the crater rim.

Plinian eruption column from May 18, 1980 Mount St. Helens. Aerial view from the Southwest.

Plinian column from May 18, 1980 eruption of Mount St. Helens. Aerial view from southwest. Mount Adams is in the background (right).

Plinian column of ash, steam, water, and debris viewed from the south of the Mount St.Helens May 18, 1980 eruption. This column reached a height of 60,000 ft (18,288 m).

Mount St. Helens on May 17, 1980, one day before the devastating eruption. The view is from Johnston's Ridge, six miles (10 kilometers) northwest of the volcano.

David Johnston at Coldwater II, 1900 hours, May 17, 1980. Dave did not survive the next day's eruption. Coldwater II would eventually be re-named "Johnston Ridge" in honor of Dave.

Bulge on the north slope of Mount St. Helens before the May 18, 1980 eruption. Sugar Bowl on left (east) side of bulge and Goat Rocks on right (west) side, viewed from the air.

A "bulge" developed on the north side of Mount St. Helens as magma pushed up within the peak. Angle and slope-distance measurements to the bulge indicated it was growing at a rate of up to five feet (1.5 meters) per day. By May 17, part of the volcano's north side had been pushed upwards and outwards over 450 feet (135 meters).